#2311
Longest Binary Subsequence Less Than or Equal to K
medium · verified · 52.8% accepted · 1,144 likes · top 43%
string · dynamic programming · greedy · memoization
Description
You are given a binary string s and a positive integer k.
Return the length of the longest subsequence of s that makes up a binary number less than or equal to k.
Note:
- The subsequence can contain leading zeroes.
- The empty string is considered to be equal to 0.
- A subsequence is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.
Example 1:
Input: s = "1001010", k = 5
Output: 5
Explanation: The longest subsequence of s that makes up a binary number less than or equal to 5 is "00010", as this number is equal to 2 in decimal.
Note that "00100" and "00101" are also possible, which are equal to 4 and 5 in decimal, respectively.
The length of this subsequence is 5, so 5 is returned.
Example 2:
Input: s = "00101001", k = 1
Output: 6
Explanation: "000001" is the longest subsequence of s that makes up a binary number less than or equal to 1, as this number is equal to 1 in decimal.
The length of this subsequence is 6, so 6 is returned.
Solution